Geometrical and energetic DFT calculations as well as GIAO and NICS chemical shifts have been calculated for
1H-azepine and 5H-dibenz[b, f]azepine and their cations. The last compound has been studied experimentally by
1H and 13C NMR in neutral and acidic conditions establishing that the cation corresponds to an N-protonated
structure. The conclusion is that the neutral molecules are antiaromatic while the cations are aromatic
(homoheteroaromaticity).